Carbamate-functional resins having improved adhesion, method of making the same, and method of improving intercoat adhesion

ABSTRACT

The invention provides carbamate-functional resins and coating compositions incorporating said resins that have improved adhesion with respect to subsequently applied films or coatings. More particularly, the invention relates to carbamate-functional addition polymers having at least 250 grams of polymer per carbamate group which are made with less than 35 percent by weight of nonfunctional monomers, preferably with less than 20 percent by weight and most preferably from 0 to less than 10 percent by weight, based on the total weight of the polymer. The invention further provides a method of making a carbamate-functional polymer and carbamate-functional polymers made by the claimed method. Finally, the invention provides a method for improving the adhesion of a first coating composition to a subsequently applied material as well as a method of making a composite comprising a coated substrate, an adhesive composition, and a glass having at least one surface.

This application claims the benefit of prior U.S. ProvisionalApplications Nos. 60/157,166, 60/157,164, and 60/157,165, all filed Sep.30, 1999.

FIELD OF THE INVENTION

The invention provides carbamate-functional resins and coatingcompositions incorporating said resins that have improved adhesion withrespect to subsequently applied films or coatings. More particularly,the invention relates to carbamate-functional addition polymers havingat least 250 grams of polymer per carbamate group which are made withless than 35 percent by weight of nonfunctional monomers, preferablywith less than 20 percent by weight and most preferably from 0 to 10percent by weight, based on the total weight of the polymer. Theinvention further provides a method of making a carbamate-functionalpolymer and carbamate-functional polymers made by the claimed method.Finally, the invention provides a method for improving the adhesion of afirst coating composition to a subsequently applied material as well asa method of making a composite comprising a coated substrate, anadhesive composition, and a glass having at least one surface.

BACKGROUND OF THE INVENTION

Clearcoat-basecoat composite coatings are widely used in the coatingsart and are notable for desirable gloss, depth of color, distinctness ofimage and/or special metallic effects. Composite systems areparticularly utilized by the automotive industry to achieve advantageousvisual effects, especially a high degree of clarity. However, a highdegree of clarity in the clearcoat makes it easier to observe defects.Defects resulting from environmental etch are particularlydisadvantageous. Environmental etch is a phenomenon which manifests asspots or marks on or in the clearcoat which are removed only with lossof clearcoat.

Clearcoat compositions containing carbamate-functional acrylic polymershave been disclosed by the prior art as a solution to the problem ofenvironmental etch.

While such polymers and compositions containing them provide asignificant improvement over the prior art, improvements in some areasare still desirable. In particular, it would be advantageous to providepolymers exhibiting improved adhesion while still possessing thepositive environmental etch and performance characteristics ofcarbamate-functional acrylics. Improvements are particularly desiredwith respect to adhesion of the polymer-containing composition to one ormore subsequently applied coatings or materials.

For example, surfaces coated with clearcoat-basecoat compositions mustsometimes be repaired or treated to correct minor defects or flaws. Suchrepairs often require the application of subsequently appliedbasecoat/clearcoat composite compositions, basecoat or clearcoatcompositions alone, or fast cure versions thereof. That portion of theoriginally applied clearcoat composition must adhere to the subsequentlyapplied basecoat/clearcoat composite composition, basecoat or clearcoatcompositions alone, and/or any other subsequently applied material ormaterials. Adhesion failures resulting from a weak bond between theoriginally applied coating and the subsequently applied coating ormaterial are known as intercoat adhesion failures. Intercoat adhesion isthus a required characteristic of coating compositions intended for usein clearcoat-basecoat compositions, especially for clearcoatcompositions intended for use in the automotive OEM markets.

While carbamate-functional polymers and compositions incorporating thesame have been disclosed in the prior art to have advantageousproperties, intercoat and repair adhesion issues remain unaddressed.

For example, U.S. Pat. No. 5,412,049 discloses copolymers which are thecopolymerization product of (a) hydroxyl (meth)acrylate ester monomersand (b) (meth)acrylate esters of hydroxyalkyl carbamate monomers. Othercomonomers based on (meth)acrylate homopolymers or copolymers andoptional ethylenically unsaturated monomers may be copolymerized withthe functional components (a) and (b) in amounts of from about 0 to 90weight percent of the total copolymer composition, more preferably from10 to 80 weight percent of the total copolymer composition, mostpreferably from about 20 to 70 weight percent of the total copolymercomposition.

However, adhesion, especially intercoat adhesion, is not discussed inthe '049 patent. Moreover, all of the working examples require the useof 55 weight percent or more of nonfunctional ethylenically unsaturatedmonomers.

U.S. Pat. No. 5,356,669 provides a curable coating compositioncomprising (a) a first component comprising a polymer backbone havingappended thereto at least one carbamate-functional group, and (b) asecond component comprising a compound having a plurality of functionalgroups that are reactive with said carbamate group. The polymercomponent (a) is represented by the formula

In this formula, A represents repeat units derived from one or moreethylenically unsaturated monomers such as alkyl esters of acrylic ormethacrylic acid, e.g., ethyl acrylate, butyl acrylate, 2-ethylhexylacrylate, butyl methacrylate, isodecyl methacrylate, hydroxyethylmethacrylate, hydroxypropyl acrylate, and the like; and vinyl monomerssuch as unsaturated m-tetramethyl vinyl isocyanate, styrene, vinyltoluene and the like, x and y represent weight percentages, with x being10 to 90% and preferably 40 to 60%, and y being 90 to 10% and preferably60 to 40%.

Thus, the prior art has failed to achieve a carbamate functional polymerhaving the desired adhesion to subsequently applied materials.

Accordingly, it is an object of the invention to providecarbamate-functional polymers that exhibit improved adhesion tosubsequently applied materials while maintaining the known advantages ofcarbamate-functional polymers.

It is a further object of the invention to provide coating compositionscontaining such carbamate-functional polymers.

It is another object of the invention to provide a method of making acarbamate-functional polymer having improved intercoat adhesionproperties as well as carbamate-functional polymers made from such amethod.

These and other objects of the invention have been achieved by theinstant invention.

It has unexpectedly been found that use of less than 35 percent byweight of nonfunctional monomers based on the total weight of thepolymer, preferably less than 20 percent and most preferably less than10 percent, results in desirable improvements in adhesion, especiallyrecoat adhesion. Even more unexpectedly, it has been found that suchimprovements in adhesion can be obtained without the loss of any of thedesirable performance, reactivity and/or application characteristicsassociated with carbamate-functional acrylics.

SUMMARY OF THE INVENTION

The invention provides a carbamate-functional polymer having a backbonemade by addition polymerization. The polymer has an equivalent weight ofat least 250 grams of polymer per carbamate group and comprises from atleast 66 to 100% by weight, based on the total weight of the polymer, ofone or more repeat units A selected from the group consisting of

and mixtures thereo, and

and from 0 to less than 35% by weight, based on the total weight of thepolymer, of one or more repeat units A′ having the structure

wherein R is an at least divalent nonfunctional linking group havingfrom 1 to 60 carbons atoms and from 0 to 20 heteroatoms selected fromthe group consisting of oxygen, nitrogen, sulfur, phosphorus, silane,and mixtures thereof, R′ is an at least monovalent nonfunctional linkinggroup having from 1 to 60 carbon atoms and from 0 to 20 heteroatomsselected from the group consisting of oxygen, nitrogen, sulfur,phosphorus, silane, and mixtures thereof, the at least monovalentnonfunctional linking group preferably having at least one branchedalkyl group of at least 5 carbons, R″ is H or a monovalent nonfunctionallinking group having from 1 to 60 carbon atoms and from 0 to 20heteroatoms selected from the group consisting of oxygen, nitrogen,sulfur, phosphorus, and silane, and mixtures thereof, L is a divalentnonfunctional linking group having from 1 to 60 carbon atoms and from 0to 20 heteroatoms selected from the group consisting of oxygen,nitrogen, sulfur, phosphorus, silane, and mixtures thereof, F, F¹ and F²are functional groups selected from the group consisting of pendantcarbamate groups, especially primary carbamate groups, hydroxyl groups,and mixtures thereof, with the proviso that at least one of F¹ and F²are a primary carbamate group or a beta-hydroxy primary carbamate group,and n is an integer from 0 to 3.

The invention also provides a method of making a carbamate-functionalpolymer having an equivalent weight of at least 250 grams of polymer percarbamate group.

The method requires the preparation of a backbone polymer comprising oneor more functional groups F′. The backbone polymer is prepared by theaddition polymerization of from at least 66 to 100% by weight, based onthe total weight of the carbamate-functional polymer, of one or moreethylenically unsaturated carbamate free monomers A having at least onefunctional group F′, and from 0 to less than 35% by weight, based on thetotal weight of the carbamate-functional polymer, of one or morenonfunctional ethylenically unsaturated monomers A′.

The resulting backbone polymer is then reacted with one or morecompounds B to make a carbamate-functional polymer having at least onecarbamate group. The one or more compounds B have at least onefunctional group (b1), which, upon reaction with either a functionalgroup F′ or the reaction product of one or more prior reactions of afunctional group (b1) and functional group F′, results in a carbamategroup.

Finally, the invention provides methods of improving the adhesion of afirst coating composition to a subsequently applied material.

The method requires the use of a first coating composition comprising apolymer having a backbone resulting from addition polymerization andhaving from 0 to less than 35 weight percent of repeat units fromnonfunctional ethylenically unsaturated monomers A′, based on the totalweight of the carbamate-functional polymer.

In another aspect of the invention, a method of making a particularcomposite is provided. The composite comprises a coated substrate, anadhesive composition, and a glass having at least one surface. To makethe coated substrate, the method requires the use of a coatingcomposition comprising a polymer having a backbone resulting fromaddition polymerization and from 0 to less than 35 weight percent ofrepeat units from nonfunctional ethylenically unsaturated monomers A′,based on the total weight of the carbamate-functional polymer. After thecoated substrate is prepared, an adhesive composition is applied to thecoated substrate, and a glass having at least one surface is adhered tothe adhesive composition to form a composite wherein the at least onesurface of the glass is adhered to the coated substrate by the adhesivecomposition. It has been found that the strength of the adhesive bondbetween the at least one surface of the glass and the coated substrateis greater than the strength of an adhesive bond in a second compositewherein a second substrate is coated with a second coating compositioncomprising a polymer having a backbone resulting from additionpolymerization and at least 35 weight percent or more of repeat unitsfrom nonfictional ethylenically unsaturated monomers A′, based on thetotal weight of the polymer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has unexpectedly been found that carbamate-functional polymers madewith from 0 to less than 35 weight percent of nonfunctionalethylenically unsaturated monomers, based on the total weight of thecarbamate-functional polymer, and coating compositions containing suchpolymers, possess advantageous intercoat or repair adhesion properties.The terms “intercoat adhesion” or “repair adhesion” as used herein referto the adhesion of a composition, especially a first coatingcomposition, to a subsequently applied material, especially asubsequently applied second coating composition. Carbamate-functional asused herein refers to pendant or terminal carbamate groups, mostpreferably primary carbamate groups.

The carbamate-functional polymers of the invention require a structurehaving a polymer backbone made via the polymerization of ethylenicallyunsaturated monomers and as such will consist substantially ofcarbon-carbon linkages. Although the carbamate-functional polymers ofthe invention may be made by addition polymerization, it is preferredthat the carbamate-functional polymer of the invention not be a true orsimple addition polymer, i.e., the polymer may have atoms and functionalgroups other than those present in the monomers polymerized to providethe polymer backbone.

Thus, in its broadest sense, the polymers of the invention may be madeby polymerization of one or more ethylenically unsaturated monomers,wherein at least 66 weight percent or more of the total weight ofpolymerized monomers contain at least one carbamate-functional group ora group convertible to a carbamate group.

One or more acrylic monomers having a carbamate-functional group in theester portion of the monomer may be used. Such monomers are well knownin the art and are described, for example in U.S. Pat. Nos. 3,479,328,3,674,838, 4,126,747, 4,279,833, and 4,340,497, the disclosures of whichare incorporated herein by reference. One method of synthesis involvesreaction of a hydroxy ester with urea to form the carbamyloxycarboxylate (i.e., carbamate-modified acrylic). Another method ofsynthesis reacts an α,β-unsaturated acid ester with a hydroxy carbamateester to form the carbamyloxy carboxylate. Yet another techniqueinvolves formation of a hydroxyalkyl carbamate by reacting ammonia, aprimary or secondary amine or diamine with a cyclic carbonate such asethylene carbonate. The hydroxyl group on the hydroxyalkyl carbamate isthen esterified by reaction with acrylic or methacrylic acid to form themonomer. Other methods of preparing carbamate-modified acrylic monomersare described in the art, and can be utilized as well.

The acrylic monomer having a carbamate functional group can then bepolymerized along with other ethylenically unsaturated monomers that mayor may not have functional groups, if desired, by techniques well knownin the art. However, the amount of nonfunctional ethylenicallyunsaturated monomer must be from 0 to less than 35 weight percent, basedon the total weight of the polymer. Preferably, the amount ofethylenically unsaturated monomers having no functional groups will befrom 0 to 20 percent and most preferably will be from 0 to less than 10percent by weight, based on the total weight of the polymer. As usedherein, the terms “nonfictional ethylenically unsaturated monomers” or“ethylenically unsaturated monomers having no functional groups” referto ethylenically unsaturated monomers which do not contain functionalgroups which are reactive with crosslinking agents, especiallyaminoplast and/or isocyanate functional crosslinking agents. Examples ofsuch reactive functional groups are pendant carbamate groups, bothsecondary and primary, and hydroxyl groups.

At a minimum, from 0 to less than 35 weight percent, preferably from 0to less than 20 percent, and most preferably from 0 to 10 or less than10 percent by weight, of ethylenically unsaturated monomers which aresubstantially free of carbamate groups, especially primary carbamategroups, and hydroxyl groups will be used, based on the total weight ofthe polymer.

Examples of nonfunctional ethylenically unsaturated monomers that may beused are the alkyl esters of acrylic acid, methacrylic acid and/orcrotonic acid such as methyl, ethyl, propyl, butyl, pentyl, hexyl,octyl, decyl, and dodecyl acrylates and methacrylates. Other examplesinclude styrene, vinyl cyclohexane, vinyl cyclooctane, vinylcyclohexene, hexanediol diacrylate, vinyl naphthalene, alphamethylstyrene, and the like.

An alternative route for preparing the carbamate functional polymer ofthe invention is to react an already-formed acrylic backbone polymerwith another component to form a carbamate-functional group appended tothe polymer backbone, as described in U.S. Pat. No. 4,758,632, thedisclosure of which is incorporated herein by reference. One techniquefor preparing a carbamate functional polymer involves thermallydecomposing urea (to give off ammonia and HNCO) in the presence of ahydroxy-functional acrylic polymer to form a carbamate-functionalacrylic polymer. Another technique involves reacting the hydroxyl groupof a hydroxyalkyl carbamate with the isocyanate group of anisocyanate-functional acrylic or vinyl monomer to form thecarbamate-functional acrylic. Isocyanate-functional acrylics are knownin the art and are described, for example in U.S. Pat. No. 4,301,257,the disclosure of which is incorporated herein by reference. Isocyanatevinyl monomers are well known in the art and include unsaturatedm-tetramethyl xylene isocyanate (sold by American Cyanamid under thetrademark TMI®). Yet another technique is to react the cyclic carbonategroup on a cyclic carbonate-functional acrylic with ammonia in order toform the carbamate-functional acrylic. Cyclic carbonate-functionalacrylic polymers are known in the art and are described, for example, inU.S. Pat. No. 2,979,514, the disclosure of which is incorporated hereinby reference. Another way is to react a hydroxyalkyl carbamate with ananahydride backbone. Alternatively, a carboxy carbamate may be reactedwith an epoxy acrylic. In fact any condensation reaction or combinationthereof may used to carbamate or post extend the polymer backbone. Amore difficult, but feasible way of preparing the polymer would be totrans-esterify an acrylate polymer with a hydroxyalkyl carbamate.

Most preferably, the carbamate-functional polymers of the invention willbe made by a two stage reaction wherein a backbone polymer is made bypolymerizing from at least 66 to 100% by weight of one or moreethylenically unsaturated carbamate free monomers A having at least onefunctional group F′ and from 0 to less than 35% by weight of one or morenonfunctional ethylenically unsaturated monomers A′, based on the totalweight of the final polymer. The backbone polymer is then reacted withone or more compounds B so as to produce a carbamate-functional polymerhaving at least one carbamate group, preferably a primary carbamategroup. The one or more compounds B have at least one fictional group(b1), which upon reaction with either a functional group F′ or thereaction product of one or more prior reactions of a functional group(b1) and functional group F′, results in a carbamate group, preferably aprimary carbamate group, being appended to the backbone polymer.

Preferably from 80 to 100 percent by weight of monomers A will be used,and most preferably from 90 percent or more, based on the total weightof the final polymer.

Monomers within the scope of ethylenically unsaturated carbamate freemonomers A having at least one functional group F′ are those which donot have any secondary or primary carbamate groups. Functional group F′may be any functional group or moiety which upon reaction with afunctional group (b1) or the prior reaction product thereof, results ina carbamate group. Functional group F′ may thus be any functional groupconvertible to a carbamate group. Examples of functional groups F′include carboxylic acid, hydroxy, cylic carbonate groups, isocyanategroups, epoxy, silane, anhydrides and mixtures thereof. Preferablyfunctional group F′ will be an epoxy group, a carboxylic acid, or ahydroxy group and mixtures thereof, most preferably, functional group F′will be a carboxylic acid group, or a hydroxy group.

Examples of suitable monomers A are methacrylic acid, acrylic acid,hydroxy alkyl esters of methacrylic acid and/or acrylic acid such ashydroxy ethyl (meth)acrylate, hydroxy propyl (meth)acrylate, and thelike, vinyl monomers such unsaturated m-tetramethyl vinyl isocyanate(sold by American Cyanamide under the trademark TMI®), glycidylmethacrylate, maleic anhydrides, isocyanate ethyl(methyl)acrylate,mixture thereof, and the like. Preferred monomers A are (meth)acrylicacid, hydroxy alkyl esters of (meth)acrylic acid and mixtures thereof.Most preferred for use as monomers A are acrylic acid, methacrylic acid,hydroxyethyl methacrylate and mixtures thereof.

Monomers suitable for use as one or more nonfunctional ethylenicallyunsaturated monomers A′ are those described above with respect to thenonfunctional ethylenically unsaturated monomers which maybecopolymerized with the carbamate functional acrylic monomers. Preferrednonfunctional ethylenically unsaturated monomers A′ are the alkyl estersof acrylic acid, methacrylic acid, styrene and mixtures thereof.Suitable alkyl esters are those having from 1 to 20 carbons, preferablyfrom 1 to 10 carbons, and most preferably from 2 to 6 carbons.

The amount of one or more nonfunctional ethylenically unsaturatedmonomers A′ used must be from 0 to less than 35 weight percent, based onthe total weight of the final polymer. Final polymer as used hereinrefers to the carbamate-functional polymer obtained after the reactionof the backbone polymer and one or more compounds B. Preferably, theamount of ethylenically unsaturated monomers A′ having no functionalgroups will be from 0 to 20 percent and most preferably will be from 0to less than 18 percent by weight, based on the total weight of thepolymer. However, amounts of from 1 to less than 10 percent, especially8 or percent or less are also acceptable.

At a minimum, from 0 to less than 35 weight percent, preferably from 0to less than 20 percent of ethylenically unsaturated monomers A′ whichare substantially free of pendant carbamate groups, especially primarycarbamate groups and hydroxyl groups will be used, based on the totalweight of the final polymer.

Monomers A and A′ may be copolymerized by a variety of polymerizationtechniques. Illustrative examples include solution polymerization,aqueous emulsion, dispersion, or suspension polymerization, bulkpolymerization, nonaqueous emulsion, dispersion, or suspensionpolymerization, and the like. Polymerization may occur in a variety ofreactor types, i.e., stirred batch reactors, tubular reactors, and thelike, all of which may be made of materials known to those skilled inthe art.

In a preferred embodiment, the addition polymerization will take placein an aromatic solvent blend having a significant portion of co-solventshaving a polar nature. As used herein, polar is defined as having adielectric constant of at least 15 (25° C.), preferably from 12-25 (25°C.), and most preferably from 18 to 22 (25° C.). However, such suitableco-solvents may not have any functionality which will interfere orpreclude subsequent secondary reactions between the backbone polymer andone or more compounds B. Examples of suitable polar co-solvents whichare not suitable for use herein are alcohols, esters, ketones, ethers,and the like. Rather, preferred co-solvents are those having afunctionality which will react with the backbone polymer. Ideally, theco-solvents will be capable of functioning as a compound B in reactionswith the backbone polymer. As discussed below, such reactions may occurduring and/or after the polymerization of monomers A and A′. Examples ofpreferred co-solvents are those having monofunctional epoxy groups orcarbamate functionality 'such as methyl carbamate, glycidylneodecanoate, and mixtures thereof.

The copolymerization of monomers A and A′ results in a backbone polymerhaving one or more functional groups F′.

The copolymerization product of monomers A and A′ will be reacted withone or more compounds B. Compound B may generally be any compound havinga functional group b1 reactive with functional group F′ or the reactionproduct of an earlier reaction between group F′ and a functional groupb1. Compound B may comprise a further functional group b2 selected fromthe group consisting of carbamate groups and groups convertible tocarbamate groups. At least one of the compounds B will react with thebackbone polymer to provide a reaction product containing a carbamategroup or a group convertible to a carbamate group. For example, ifcompound B contains both b1 and b2, wherein b2 is a primary carbamategroup, reaction of functional group F′ with functional group b1 willresult in a reaction product containing a primary carbamate groupappended to the backbone polymer. It will be appreciated that thereaction of other compounds B with the backbone polymer may result innoncarbamate group containing reaction products.

Examples of functional groups b1 and b2 include carbamate, glycidyl,hydroxy, isocyanate, cyclic carbonates, phosgene, triphosgene, NH₃,amines, carboxylic acids, anhydrides, epoxy, mixtures thereof, and thelike.

Illustrative examples of compound B include beta-hydroxy carbamates suchas hydroxy propyl carbamate, e-caprolactone, alkyl carbamates, glycidylcompounds such as glycidyl neodecanoate and the like, anhydrides such assuccinic anhydride, acid carbamates, amino carbamates, and mixturesthereof. Preferred examples are methyl carbamate, glycidyl neodecanoate,and mixtures thereof.

Illustrative examples of the reaction product of monomers A and A′ withone or more compounds B are provided as follows.

An acid functional backbone polymer may be reacted with an epoxyfunctional compound B. The resultant hydroxy may be reacted with afurther compounds B such as e-caprolactone, octanoic acid ortranscarbamated.

An isocyanate or acid functional backbone polymer may be reacted with abeta hydroxy carbamate such as hydroxy propyl carbamate.

An epoxy functional backbone may be made by either homopolymerizingglycidyl methacrylate or copolymerizing glycidyl methacrylate with lowlevels of nonfunctional monomers, i.e., less than 35%, preferably from 1to 10, and most preferably less than 9%, based on the total weight ofthe final resulting carbamate functional polymer. The homopolymer orcopolymer is then made carbamate functional via reaction of the epoxygroups with a carboxylic acid functional and primary carbamatecontaining compound. An illustrative acid carbamate is the reactionproduct of succinic anhydride and hydroxy propyl carbamate.

The reaction of the backbone polymer and the one or more compounds B maytake place before, during or after polymerization of the ethyenicallyunsaturated monomers A and A′.

The carbamate-functional polymers of the invention will generally have anumber average molecular weight of from 800 to 50,000, more preferablyfrom 1000 to 5000, and most preferably from 1,500 to 3000. Molecularweight can be determined by the GPC method using a polystyrene standard.

The carbamate content of the polymer, on a molecular weight equivalentof carbamate functionality, will be at least 250 grams of polymer percarbamate group, more preferably between 300 and 600, and mostpreferably from 350 to 500. Equivalent weight as used herein refers onlyto primary carbamates and does not include any secondary carbamateswithin the scope of R, R′ or R″.

The glass transition temperature, T_(g) should be between −100° C. and+200° C., more preferably between 0 and 150, and most preferably from 25to 100° C.

A preferred carbamate functional polymer of the invention will have anumber average molecular weight of from 1000 to 5000, a carbamateequivalent weight of from 300 to 600, and a Tg of from 0 to 150° C. Amost preferred carbamate-functional polymer of the invention will have anumber average molecular weight of from 1500 to 3000, a carbamateequivalent weight of from 350 to 500, and a Tg of from 25 to 100° C.

The carbamate functional polymer of the invention will have from atleast 66 to 100% by weight, based on the total weight of the polymer, ofone or more repeat units A selected from the group consisting of

and mixtures thereof, and

from 0 to less than 35% by weight, based on the total weight of thepolymer, of one or more repeat units A′ having the structure

More preferably, the carbamate functional polymer of the invention willhave from 80 to 100 weight percent of one or more repeat units A andfrom 20 to 0 weight percent of one or more repeat units A′, and mostpreferably, from 90 to 100 weight percent of one or more repeat units Aand from 10 to 0 weight percent of one or more repeat units A′, based onthe total weight of the final carbamate functional polymer. Aparticularly preferred carbamate functional polymer of the inventionwill have more than 90 weight percent of one or more repeat units A andless than 10 weight percent, preferably between 1 and 9 weight percent,of one or more repeat units A′, based on the total weight of thecarbamate functional polymer of the invention.

In the above, R is an at least divalent nonfunctional linking grouphaving from 1 to 60 carbon atoms and from 0 to 20 heteroatoms selectedfrom the group consisting of oxygen, nitrogen, sulfur, phosphorus, andsilane, and mixtures thereof As used here, “nonfunctional” refers to theabsence of groups which are reactive with crosslinking agents undertraditional coating curing conditions.

Illustrative examples of suitable R groups are aliphatic orcycloaliphatic linking groups of from 1 to 60 carbons, aromatic linkinggroups of from 1 to 10 carbons, and mixtures thereof Preferred R groupsinclude aliphatic or cycloaliphatic groups of from 2 to 10 carbons. Rmay, and preferably will, include one or more heteroatoms via one ormore divalent internal linking groups such as esters, amides, secondarycarbamates, ethers, secondary ureas, ketones, and mixtures thereof.Internal linking groups selected from the group consisting of esters,secondary carbamates, and mixtures thereof, are more preferred, withesters being most preferred.

Examples of particularly preferred R groups are set forth below. Notethat F¹ is not part of R but is shown in the structures below to provideperspective.

and isomers thereof, wherein X is H or is a a monovalent nonfictionallinking group having from 1 to 20 carbon atoms and from 0 to 20heteroatoms selected from the group consisting of oxygen, nitrogen,sulfur, phosphorus, and silane, and mixtures thereof; i, j, g, and h areintergers from 0 to 8; and Q is an at least divalent nonfunctionallinking group having from 1 to 60 carbon atoms and from 0 to 20heteroatoms selected from the group consisting of oxygen, nitrogen,sulfur, phosphorus, and silane, and mixtures thereof.

A most preferred R group is

wherein j is from 1 to 6 and X is as defined above.

R′ is an at least monovalent nonfunctional linking group having from 1to 60 carbon atoms and from 0 to 20 heteroatoms selected from the groupconsisting of oxygen, nitrogen, sulfur, phosphorus, and silane, andmixtures thereof. As used here, “nonfictional” refers to the absence ofgroups which are reactive with crosslinking agents under traditionalcoating curing conditions.

Illustrative examples of suitable R′ groups are aliphatic orcycloaliphatic linking groups of from 1 to 60 carbons, aromatic linkinggroups of from 1 to 10 carbons, and mixtures thereof. Preferred R′groups include aliphatic or cycloaliphatic groups of from 2 to 10carbons. R′ may, and preferably will, include one or more heteroatomsvia one or more divalent internal linking groups such as esters, amides,secondary carbamates, ethers, secondary ureas, ketones, and mixturesthereof The use of esters as internal linking groups is most preferred.

Examples of particularly preferred R′ groups are

wherein x and y are from 0 to 10, preferably from 3 to 8.

In a preferred embodiment, the at least monovalent nonfunctional linkinggroup R′ will comprise at least one branched alkyl group of from 5 to 20carbons, preferably from 5 to 15 carbons and most preferably from 8 to12 carbons. An example of an especially suitable structure forincorporation into linking group R′ is

wherein R₁, R₂, and R₃ are alkyl groups of from 1 to 10 carbons each.Most preferably, R₁, R₂, and R₃ will total from 8 to 12 carbons with atleast one of R₁, R₂, and R₃ being a methyl group. In a most preferredemodiment, n will be 0 when R′ comprises this branched alkyl structure.

R″ is H or a monovalent nonfunctional linking group having from 1 to 20carbon atoms and from 0 to 20 heteroatoms selected from the groupconsisting of oxygen, nitrogen, sulfur, phosphorus, and silane, andmixtures thereof

Illustrative examples of suitable R″ groups are hydrogen, aliphatic orcycloaliphatic linking groups of from 1 to 60 carbons, aromatic linkinggroups of from 1 to 10 carbons, and mixtures thereof. R″ may, andpreferably will, include one or more heteroatoms via one or moredivalent internal linking groups such as esters, amides, secondarycarbamates, ethers, secondary ureas, ketones, and mixtures thereof.

Preferred R″ groups are H, -CH₃, aromatic groups such as benzyl, andalkyl esters of from 2 to 10 carbons, especially from 4 to 8 carbons. Hand methyl are most preferred as R″.

L is an at least trivalent nonfunctional linking group having from 1 to60 carbon atoms and from 0 to 20 heteroatoms selected from the groupconsisting of oxygen, nitrogen, sulfur, phosphorus, and silane, andmixtures thereof. As used here, “nonfunctional” refers to the absence ofgroups which are reactive with crosslinking agents under traditionalcoating curing conditions.

Illustrative examples of suitable L groups are aliphatic orcycloaliphatic linking groups of from 1 to 60 carbons, aromatic linkinggroups of from 1 to 10 carbons, and mixtures thereof Preferred L groupsinclude aliphatic or cycloaliphatic groups of from 2 to 10 carbons. Lmay, and preferably will, include one or more heteroatoms via one ormore divalent internal linking groups such as esters, arnides, secondarycarbamates, ethers, secondary ureas, ketones, and mixtures thereofInternal linking groups selected from the group consisting of esters,secondary carbamates, and mixtures thereof, are more preferred, withesters being most preferred.

An example of preferred L groups are

and isomers thereof, wherein F¹ and R are as described, x and y may thesame or different and are from 0 to 10, preferably from 1 to 3, and ismost preferably 1.

F, F¹ and F² are functional groups selected from the group consisting ofprimary carbamate groups, hydroxyl groups, and mixtures thereof, such asbeta-hydroxy primary carbamate groups, with the proviso that at leastone of F¹ and F² are a primary carbamate group or a beta-hydroxy primarycarbamate group, and

n is an integer from 0 to 3, most preferably 0.

The carbamate functional polymer of the invention may be used in varietyof ways but will most preferably be utilized in a coating composition asa principal film forming component (a). Illustrative coatingcompositions within the scope of the instant invention include but arenot limited to primer compositions, basecoat compositions, clearcoatcompositions and/or variations thereof.

The coating compositions of the invention provide a variety ofunexpected benefits. For example, as indicated below in the workingexamples, coating compositions of the invention demonstrate improvedintercoat or repair adhesion as well as improved scratch and marresistance. In addition, the coating compositions of the inventiondemonstrate significant adhesion to primerless polyurethane adhesivessuch as are used in the calking and sealing of automotive windshieldcomposites.

In general coatings compositions of the invention may be cured by areaction of the carbamate-functional polymer component (a) with one ormore crosslinking components (b). At least one of component (b) musthave a plurality of functional groups which are reactive with thecarbamate groups on component (a). Such required reactive groups includeactive methylol or methylalkoxy groups on aminoplast crosslinking agentsor on other compounds such as phenol/formaldehyde adducts, siloxanegroups, anhydride groups and mixtures thereof. In addition, otherreactive groups may be used which are reactive with thenoncarbamate-functional groups of the carbamate-functional polymercomponent (a), i.e, hydroxyl groups. Examples of such other suitablereactive groups for use in component (b) are isocyanate, epoxy,carboxylic, siloxane, activated esters, anhydride, and mixtures thereofIf both types of reactive groups are utilized, such groups may be foundon the same or different components (b). Illustrative examples of (b)compounds incorporating such required reactive groups include melaamineformaldehyde resin (including monomeric or polymeric melamine resin andpartially or fully alkylated melamine resin), urea resins (e.g.,methylol ureas such as urea formaldehyde resin, alkoxy ureas such asbutylated urea formaldehyde resin), polyanhydrides (e.g., polysuccinicanhydride), polysiloxanes (e.g., trimethoxy siloxane), isocyanatefunctional resins, functional acrylics such as acid, isocyanate, and/oraminoplast functional acrylics, and mixtures thereof. Aminoplast resinsuch as melamine formaldehyde resin or urea formaldehyde resin areespecially preferred. Most preferred for use as one or more components(b) are mixtures of crosslinking agent such as aminoplast resins andisocyanate functional resins.

It will be further appreciated that coating compositions of theinvention may further comprise, in addition to the carbamate-functionalpolymer component (a) of the invention and one or more crosslinkingcomponents (b), additional film-forming components such aspolyurethanes, polyesters, acrylics, polyethers, and mixtures thereof.

A solvent may optionally be utilized in the coating compositions of thepresent invention. Although the composition used according to thepresent invention may be utilized, for example, in the form ofsubstantially solid powder, or a dispersion, it is often desirable thatthe composition is in a substantially liquid state, which can beaccomplished with the use of a solvent. This solvent should act as asolvent with respect to both the carbamate-functional polymer (a) aswell as the component (b). In general, depending on the solubilitycharacteristics of components (a) and (b), the solvent can be anyorganic solvent and/or water. In one preferred embodiment, the solventis a polar organic solvent. More preferably, the solvent is a polaraliphatic solvents or polar aromatic solvents. Still more preferably,the solvent is a ketone, ester, acetate, aprotic amide, aproticsulfoxide, or aprotic amine. Examples of useful solvents include methylethyl ketone, methyl isobutyl ketone, m-amyl acetate, ethylene glycolbutyl ether-acetate, propylene glycol monomethyl ether acetate, xylene,N-methylpyrrolidone, or blends of aromatic hydrocarbons. In anotherpreferred embodiment, the solvent is water or a mixture of water withsmall amounts of aqueous co-solvents.

The coating compositions of the invention may include a catalyst toenhance the cure reaction. For example, when aminoplast compounds,especially monomeric melamines, are used as component (b), a strong acidcatalyst may be utilized to enhance the cure reaction. Such catalystsare well-known in the art and include, for example, p-toluenesulfonicacid, dinonylnaphthalene disulfonic acid, dodecylbenzenesulfonic acid,phenyl acid phosphate, monobutyl maleate, butyl phosphate, and hydroxyphosphate ester. Other catalysts that may be useful in the compositionof the invention include Lewis acids, zinc salts, and tin salts.

In a preferred embodiment of the invention, the solvent is present inthe coating compositions of the invention in an amount of from about0.01 weight percent to about 99 weight percent, preferably from about 10weight percent to about 60 weight percent, and more preferably fromabout 30 weight percent to about 50 weight percent, based on the totalweight of the coating composition.

The coating compositions of the invention may further compriseadditional additives and components such as leveling agents, flowmodifers, adhesion modifiers, UV absorbers, HALS compounds,antioxidants, wetting agents, and the like. However, it has been foundthat the use of certain additives with the carbamate functional polymerof the invention provide unexpected advantages over other additives.

For example, it has unexpectedly been found that many traditional flowand/or leveling agents do not provide adequate performance when combinedwith the carbamate functional polymer of the invention. In fact, manyshow negative effects. For example, it has been found that many levelingand flow agents negatively affect the repairability of the coatingcomposition, particularly with waterborne coating compositions such aswaterborne basecoat compositions. This ability to be recoated or ‘wetout’ by subsequently applied coating compositions is necessary forautomotive coating compositions. Finally, such traditional flow,leveling and/or wetting agents must not negatively affect the popresistance of the coating compositions. “Pop” is generally referred toas holes or blemishes in the finished film which are believed to be dueto the exiting of volatile substances from the at least partially curedfilm.

It has now been found that certain preferred flow agents provide thedesired leveling, flow and recoatability properties when used with thecarbamate functional polymers of the invention. Such preferred flowadditives can generally be described as falling within one of fourparticular types of flow agents. Polyvinyl acrylic copolymers, hydroxylfunctional polyether polysiloxanes, halogenated polysiloxanes andmixtures thereof, have been found to be suitable for use in the instantinvention, with hydroxyl functional polyether polysiloxanes being mostpreferred. Illustrative commercially available examples of these typesof preferred flow additives are Byk 373 (hydroxyl polyether polydimethylpolysiloxane) commercially available from Byk Chemie, Disparlon™ LC955(vinyl acrylate copolymer) commercially available from KyoeishaChemical, Silwet™ L-7614 (hydroxyl functional polyether modifiedpolysiloxane) commercially available from Witco Chemical, and Addid™ 761(fluorinated polysiloxane) commercially available from Wacker Chemical.Silwet™ L-7614 is a most preferred flow additive for use in the instantcoating compositions.

Such preferred flow additives will generally be used in the coatingcompositions of the invention in amounts of from 0.03 to 2.0%, based ontotal resin solids, with ranges of from 0.1 to 0.8% being preferred, andranges of from 0.3 to 0.5% being most preferred, all being based ontotal resin solids.

In another aspect of the invention, it has been found that only certainpreferred hindered amine light stabilizers, hereafter referred to asHALS compounds, provide desireable results when combined with thecarbamate functional polymers of the invention. For example, it has beenfound that many traditional HALS agents are incompatible with the polarcarbamate polymers of the invention. It has now been found that HALShaving a molecular weight of at less than 300, most preferable less than260 provide desirable performance properties when combined with thecarbamate functional polymer of the invention. Such incompatible HALSextrude from the finished film and fail to provide the desired long termdurability performance characteristics.

Illustrative commercially available examples of suitable HALS areSanduvor 3058 and Tinuvin 292, with being Sanduvor 3058 most preferred.

Most preferably, the carbamate functional polymers of the invention willfind utility in clearcoat compositions used in the production ofcomposite coatings used in the automotive industry. Composite coatingsare generally produced by the application of a basecoat composition to abare, primed and/or electrocoated substrate, but preferably a primedand/or electrocoated substrate. The clearcoat is then applied to thebasecoat. The basecoat may be cured or uncured but will preferably be ina substantially uncured state. Thus, the coating compositions of theinvention are especially useful in producing wet-on-wet compositecoatings.

Pigmented basecoat compositions for such composite coatings arewell-known in the art, and do not require explanation in detail herein.Polymers known in the art to be useful in basecoat compositions includeacrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyds, andpolysiloxanes. Preferred polymers include acrylics and polyurethanes. Inone preferred embodiment of the invention, the basecoat composition alsoutilizes a carbamate-functional acrylic polymer. Basecoat polymers arepreferably crosslinkable, and thus comprise one or more type ofcross-linkable functional groups. Such groups include, for example,hydroxy, isocyanate, amine, epoxy, acrylate, vinyl, silane, acetoacetategroups and mixtures thereof. These groups may be masked or blocked insuch a way so that they are unblocked and available for thecross-linking reaction under the desired curing conditions, generallyelevated temperatures. Useful cross-linkable functional groups includehydroxy, epoxy, acid, anhydride, silane, acetoacetate groups andmixtures thereof. Preferred cross-linkable functional groups includehydroxy functional groups, amino functional groups and mixtures thereof.

Basecoat polymers may be self-cross-linkable, or may require a separatecross-linking agent that is reactive with the functional groups of thepolymer. When the polymer comprises hydroxy functional groups, forexample, the cross-linking agent may be an aminoplast resin, isocyanateand blocked isocyanates (including isocyanurates), acid or anhydridefunctional cross-linking agents or and mixtures thereof.

The coating compositions of the invention can be applied to an articleby any of a number of techniques well-known in the art. These include,for example, spray coating, dip coating, roll coating, curtain coating,and the like. For articles such as automotive body panels, spray coatingis preferred. Articles which may coated with the compositions of theinvention may be plastic, metal, wood, and mixtures thereof, withplastics and metal being preferred and metals such as steel, aluminumand the like being most preferred. Such substrates may be coated oruncoated, treated or untreated, and mixtures thereof. Most preferably,the articles or substrates to be coated with the compositions of theinvention will be primed or electrocoated.

After an article is coated with one or more applications of the coatingcompositions of the invention, it is subjected to conditions so as tocure the applied coating layers. Although various methods of curing maybe used, heat-curing is preferred. Generally, heat curing is effected byexposing the coated article to elevated temperatures provided primarilyby radiative heat sources. Curing temperatures will vary depending onthe particular blocking groups used in the cross-linking agents, howeverthey generally range between 93° C. and 177° C., and are preferablybetween 121° C. and 141° C. The curing time will vary depending on theparticular components used, and physical parameters such as thethickness of the layers, however, typical curing times range from 15 to60 minutes.

The following examples are illustrative of the claimed invention but arenot intended to limit the scope of the invention.

EXAMPLE 1 (B-F) Example IB Preparation of a Carbamate Functional Polymer(Resin IB) According to the Invention

690.9 parts of n-methyl pyrrolidone was heated to 120° C. under an inertatmosphere. Then a mixture of 912 parts of the cyclic carbonate ofglycidyl methacrylate, 228 parts of styrene, 114 parts of2,2′-azobis(2-methylbutanenitrile) and 150 parts of n-methyl pyrrolidonewas added over 2 hours and 15 minutes. The reaction mixture was held at120° C. for two hours then cooled to room temperature. Then 1400 partsof methanol was added and ammonia gas added to the reaction mixtureuntil the reaction was complete. During this time, 30 parts of thereaction mixture was removed for sampling. The excess ammonia andmethanol were then removed by vacuum distillation and 791.6 parts of εcaprolactone added. The reaction mixture was then heated under an inertatmosphere to 86° C. 3.4 parts of Fascat® 2003 (Elf Atochem) wassubsequently added and the reaction mixture heated to 130° C. Thereaction mixture was held at 130° C. until the reaction was complete.Then 287.9 parts of amyl acetate was added. The resulting resin had a NVof 65.0% and a % nonfunctional monomer of approximately 11%, based onthe total weight of the polymer.

Example IC Preparation of a Carbamate Functional Polymer (Resin IC)According to the Invention

690.9 parts of n-methyl pyrrolidone was heated to 120° C. under an inertatmosphere. A mixture of 912 parts of the cyclic carbonate of glycidylmethacrylate, 228 parts of n-butyl acrylate, 114 parts of2,2′-azobis(2-methylbutanenitrile) and 150 parts of n-methyl pyrrolidonewas then added over 2 hours and 45 minutes. The resulting reactionmixture was held at 120° C. for 1 hour and 40 minutes then cooled toroom temperature. 1050 parts of methanol were then added and ammonia gasadded to the reaction mixture until the reaction was complete. Excessammonia and methanol were then removed by vacuum distillation and 791.6parts of ε caprolactone added. The reaction mixture was then heated to50° C. under an inert atmosphere. 3.44 parts of Fascat® 2003 was addedand the reaction mixture heated to 130° C. The reaction mixture was heldat 130° C. until the reaction was complete followed by the addition of287.9 parts of amyl acetate. The resulting resin had a NV of 63.2% and a% nonfunctional monomer of approximately 11%, based on the total weightof the polymer.

Example ID Preparation of a Carbamate Functional Polymer (Resin IDAccording to the Invention

794.5 parts of amyl acetate was heated to reflux under an inertatmosphere and then cooled to 130° C. A mixture of 618.8 parts ofisocyanato ethyl methacrylate, 421.9 parts of butyl acrylate, 105.3parts of styrene, and 137.5 parts of 2,2′-azobis(2-methylbutanenitrile)was then added to the reaction mixture over 2 hours and 5 minutes. Theresulting reaction mixture was held at 130° C. for 1 hour and 50minutes, then cooled to room temperature. 0.7 parts of dibutyl tindilaurate was then charged into the reaction mixture and 414 parts ofhydroxy propyl carbamate added slowly to the reaction mixture andallowed to react. 50 parts of isobutyl alcohol was then added followedby 396.7 parts of amyl acetate. The resulting resin had a NV of 58.65%and a % nonfictional monomer of approximately 31.2, based on the totalweight of the polymer.

Example IE Preparation of a Carbamate Functional Polymer (Resin IE)According to the Invention.

267.4 parts of xylene was heated to 140° C. under an inert atmosphere. Amixture of 235.8 parts of hydroxy ethyl methacrylate, 65.9 parts ofstyrene, 357 parts of glycidyl neodecanoate, 79 parts of xylene and 79parts of 2,2′-azobis(2-methylbutanenitrile) was then added to thereaction mixture over 2 hours and 40 minutes. 3.3 parts of2,2′-azobis(2-methylbutanenitrile) and 65.9 parts of xylene was thenadded over 1 hour. The mixture was cooled to 70° C. To 1126 parts ofthis reaction mixture was added 17.4 parts of glycidyl neodecanoate. Thereaction mixture was heated to 77° C. and 176.7 parts of methylcarbamate, 5.26 parts of dibutyl tin dilaurate, and 406 parts of toluenewere added. The reaction was heated to reflux for 13 hours. Once thereaction was complete, the solvent and excess unreacted materials wereremoved by vacuum stripping, followed by the addition of 250 parts ofamyl acetate. The final resin had a NV of 72.7% and a % nonfunctionalmonomer of approximately 8.5%, based on the total weight of the polymer.

Comparative Example IF Preparation of a Carbamate Functional Polymer(Resin IF) According to the Prior Art

A mixture of 275.7 parts of xylene and 379.2 parts of methyl carbamatewas heated under an inert atmosphere to between 136 and 138° C. Amixture of 506.2 parts of hydroxy ethyl methacrylate, 759.6 parts ofstyrene, 264.2 parts of xylene, 38 parts of octanethiol, and 151.9 partsof 2,2′-azobis(2-methylbutanenitrile) was added over 1 hour and 50minutes. 25 parts of xylene was then added and the reaction mixturecooled to room temperature. Then 7.9 parts of dibutyl tin oxide and 300parts of toluene were added and the reaction mixture heated to reflux.Once the reaction was complete, the solvent and excess unreactedmaterials were removed by vacuum stripping. Then 962 parts of amylacetate was added. The final resin had a NV of 77.3% and a %nonfunctional monomer of approximately 49.5%, based on the total weightof the polymer.

EXAMPLE II (A-F) Preparation of Clearcoat Coating Compositions Accordingto the Invention (IIB-IIE) and the Prior Art (IIA & IIF)

Clearcoat compositions based on a carbamate functional resin, melamine,catalyst, a PBA flow agent, a HALS, two UVAs and a solvent wereprepared. A carbamate functional acrylic control prepared according tothe disclosures of U.S. Pat. No. 5,552,497, example 1, was used as ResinA for the preparation of comparative clearcoat coating composition IIA.Resins (IB)-(IF) were respectively used to prepare clearcoat coatingcompositions (IIB) through (IIF).

The melamine was Cymel® 323 from Cytec Industries and was used in anamount corresponding to a 1:1 carbamate:methoxy ratio. The catalyst wasNacure® XC-6206, commercially available from King Industries and used inan amount of 1.2% DDBSA based on total resin solids. The flow agent was0.1% Lindron 22 PolyButyl Acrylate commecially available from LindauChemicals, based on total resin solids. The HALS was 1.5% Tinuvin® 123HALS commercially available from Ciba Speciality Chemicals, and based ontotal resin solids. The two UVAs were 2.2% of Tinuvin® 928 BenzotriazoleUVA and 0.9% of Tinuvin® 400 Triazine UVA, both based on the total resinsolids and commercially available from Ciba Speciality Chemicals. Themonomethyl ether of propylene glycol (Dowanol™ PM) was added such thatthe final compositions had a viscosity of 35 seconds on a #4 Ford Cupviscometer at 25° C.

EXAMPLE III Repair Adhesion of Clearcoat Coating Compositions (IIA-IIF)

The repair adhesion of clearcoat coating compositions (IIA-IIF) wastested as follows. Test panels (IIIA-IIIF) were prepared by primingpreviously electrocoated cold rolled steel panels. The primer wasapplied to an approximately 1.0 mil dry film thickness and was asolventborne polyester/melamine based composition commercially availablefrom BASF Corporation as U28AK215. The primer was then cured perrecommended curing conditions. A waterborne black basecoat, commerciallyavailable from BASF Corporation as E202KW706, was then applied to theprimed panel for a dry film build of from 0.6 to 0.7 mils and flashedfor 5 minutes at 140 degrees F. Clearcoat compositions IIA, IIB, IIC,IID, IIE, and IIF were then spray applied to the flashed basecoatedpanels in a dry film build wedge of from 0.1 to 2.0 mils. The appliedclearcoat compositions were then flashed for 20 minutes at roomtemperature. The panels were then cured for 90 minutes at 300 degrees F.to simulate an overbake condition. A repair condition was simulated bythe application of the previously applied black waterborne basecoat tothe overbaked clearcoated panels. No scuffy or abrasion was provided tothe overbaked clearcoated panels. The ‘repair’ basecoat was applied asindicated above followed by application of the same correspondingclearcoat to the flashed but uncured basecoat. The clearcoat was appliedto a dry film build of 2.0 mils. The clearcoat was the flashed for 20minutes at room temperature and baked for 15 minutes at 260 degrees F.

Adhesion was evaluated per GM 9071P, hereby incorporated by reference.The results are set forth in Table 1.

TABLE 1 % Nonfunctional Coating Composition Monomer % Adhesion RemainingIIA (Comparative) 55.1% 0% IIB 11%  98% IIC 11%  100% IID 31.2% 95% IIE 8.5% 90% IIF (Comparative) 49.5% 10%

It can thus be seen that coating compositions containing the carbamatefunctional resins of the invention exhibit improved repair adhesionrelative to coating compositions containing prior art carbarmatefunctional resins.

EXAMPLE IV (A-E) Preparation of Carbamate Functional PolymersIllustrating the effect of % Nonfunctional Monomer upon Repair AdhesionExample IVA Preparation of a Carbamate Functional Polymer (Resin IVA)According to the Invention

1973 parts of xylene, 1356.1 parts methyl carbamate and 2032 partsglycidyl neodecanoate were heated to 140° C. under an inert atmosphere.A mixture of 1718.4 parts of hydroxy ethyl methacrylate, 479.9 parts ofstyrene, 576 parts of acrylic acid, 552 parts of xylene and 576.1 partsof 2,2′-azobis(2-methylbutanenitrile) was added to the reaction mixtureover 3.5 hours. The reaction mixture was slowly cooled to 110° C. 23.9parts of 2,2′-azobis(2-methylbutanenitrile) and 200 parts of xylene wereadded over 1 hour. The reaction mixture was heated to 140° C. for 6.5hours after which 28.3 parts of dibutyl tin oxide and 500 parts oftoluene were added. The reaction was heated to reflux for 7.5 hours.Once the reaction was complete, the solvent and excess unreactedmaterials were removed by vacuum stripping, followed by the addition of2186 parts of monomethyl ether of propylene glycol. The final resin hada NV of 69.59% and a % nonfunctional monomer of approximately 8.4%,based on the total weight of the polymer.

Example IVB Preparation of a Carbamate Functional Polymer (Resin IVB)According to the Invention

689.5 parts of xylene, 473.9 parts methyl carbamate and 710.1 partsglycidyl neodecanoate were heated to 140° C. under an inert atmosphere.A mixture of 600 parts of hydroxy ethyl methacrylate, 167.7 parts ofstyrene, 240.7 parts of methacrylic acid, 192 parts of xylene and 206.3parts of 2,2′-azobis(2-methylbutanenitrile) was added to the reactionmixture over 2.25 hours. The reaction mixture was slowly cooled to 115°C. 8.4 parts of 2,2′-azobis(2-methylbutanenitrile) and 69.9 parts ofxylene were added over 1 hour. The reaction mixture was heated to 140°C. for 7 hours after which 9.9 parts of dibutyl tin oxide and 350 partsof toluene were added. The reaction was heated to reflux for 5.25 hours.Once the reaction was complete, the solvent and excess unreactedmaterials were removed by vacuum stripping, followed by the addition of844.9 parts of monomethyl ether of propylene glycol. The final resin hada NV of 68.97% and a % nonfunctional monomer of approximately 8.1, basedon the total weight of the polymer.

Example IVC Preparation of a Carbamate Functional Polymer (Resin IVC)According to the Invention

731.6 parts of xylene, 445.4 parts methyl carbamate and 692.3 partsglycidyl neodecanoate were heated to 140° C. under an inert atmosphere.A mixture of 593.6 parts of hydroxy ethyl methacrylate, 163.6 parts of2-ethylhexyl acrylate, 234.7 parts of methacrylic acid, 202.1 parts ofxylene and 202.1 parts of 2,2′-azobis(2-methylbutanenitrile) was addedto the reaction mixture over 2.25 hours. The reaction mixture was slowlycooled to 115° C. 33.7 parts of 2,2′-azobis(2-methylbutanenitrile) and101 parts of xylene were added over 1 hour. The reaction mixture washeated to 140° C. for 5.75 hours after which 9.8 parts of dibutyl tinoxide and 300 parts of toluene were added. The reaction was heated toreflux for 6 hours. Once the reaction was complete, the solvent andexcess unreacted materials were removed by vacuum stripping, followed bythe addition of 797.5 parts of monomethyl ether of propylene glycol. Thefinal resin had a NV of 67.78% and a % nonfunctional monomer ofapproximately 8.2, based on the total weight of the polymer.

Example IVD Preparation of a Carbamate Functional Polymer (Resin IVD)According to the Invention

731.6 parts of xylene, 445.4 parts methyl carbamate and 542.6 partsglycidyl neodecanoate were heated to 140° C. under an inert atmosphere.A mixture of 593.6 parts of hydroxy ethyl methacrylate, 363.8 parts of2-ethylhexyl acrylate, 184.1 parts of methacrylic acid, 202.1 parts ofxylene and 202.1 parts of 2,2′-azobis(2-methylbutanenitrile) was addedto the reaction mixture over 3.25 hours. The reaction mixture was slowlycooled to 115° C. 33.7 parts of 2,2′-azobis(2-methylbutanenitrile) and101 parts of xylene were added over 1 hour. The reaction mixture washeated to 140° C. for 6 hours after which 9.8 parts of dibutyl tin oxideand 300 parts of toluene were added. The reaction was heated to refluxfor 7.5 hours. Once the reaction was complete, the solvent and excessunreacted materials were removed by vacuum stripping, followed by theaddition of 799.3 parts of monomethyl ether of propylene glycol. Thefinal resin had a NV of 68.51% and a % nonfunctional monomer ofapproximately 18.2%, based on the total weight of the polymer.

Example IVE Preparation of a Carbamate Functional Polymer (Resin IVE)According to the Invention

731.6 parts of xylene, 445.4 parts methyl carbamate and 393.2 partsglycidyl neodecanoate were heated to 140° C. under an inert atmosphere.A mixture of 593.6 parts of hydroxy ethyl methacrylate, 564.1 parts of2-ethylhexyl acrylate, 133.3 parts of methacrylic acid, 202.1 parts ofxylene and 202.1 parts of 2,2′-azobis(2-methylbutanenitrile) was addedto the reaction mixture over 3.25 hours. The reaction mixture was slowlycooled to 115° C. 33.7 parts of 2,2′-azobis(2-methylbutanenitrile) and101 parts of xylene were added over 1 hour. The reaction mixture washeated to 140° C. for 6 hours after which 9.8 parts of dibutyl tin oxideand 300 parts of toluene were added. The reaction was heated to refluxfor 4.75 hours. Once the reaction was complete, the solvent and excessunreacted materials were removed by vacuum stripping, followed by theaddition of 804.9 parts of monomethyl ether of propylene glycol. Thefinal resin had a NV of 68.87% and a % nonfunctional monomer ofapproximately 28.2%, based on the total weight of the polymer.

EXAMPLE V (A-F) Preparation of Clearcoat Compositions Illustrating theEffect of % Nonfunctional Monomer upon Repair Adhesion

Clearcoat compositions based on a carbamate functional resin, melamine,catalyst, a flow agent, a HALS, two UVAs and a solvent were prepared. Acarbamate functional acrylic control prepared according to thedisclosures of U.S. Pat. No. 5,552,497, example 1, was used as Resin Ffor the preparation of comparative clearcoat coating composition IVF.Resins (IB)-(IF) were respectively used to prepare clearcoat coatingcompositions (IIB) through (IIF).

The melamine was BM 9539, commercially available from Monsanto and wasused in an amount corresponding to a 1:1 carbamate:methoxy ratio. Thecatalyst was Nacure® XC-6206, commercially available from KingIndustries and used in an amount of 1.2% DDBSA based on total resinsolids. The flow agent was 0.1% Disparlon™ LC 955, commecially availablefrom King Industries, and based on total resin solids. The HALS was 1.5%Sandovar 3056, commercially available from Clariant Industries, andbased on total resin solids. The two UVAs were 2.2% of Tinuvin® 928 and0.9% of Tinuvin® 400 Triazine UVA, both based on the total resin solidsand commercially available from Ciba Speciality Chemicals. The solventwas propylene glycol methyl ether and was used in an amount sufficientto provide coating compositions having a 35 sec viscosity on a #4 Fordcup @ 80 degrees F.

EXAMPLE VI Repair Adhesion of Clearcoat Coating Compositions (VA-VF)

The repair adhesion of clearcoat coating compositions (VA-VF) was testedas follows. Test panels (VIA-VIF) were prepared by priming previouslyelectrocoated cold rolled steel panels. The primer was applied to anapproximately 1.0 mil dry film thickness and was a solventbornepolyester/melamine based composition commercially available from BASFCorporation as U28AK215. The primer was then cured per recommendedcuring conditions. A waterborne white basecoat, commercially availablefrom BASF Corporation as E202WW709, was then applied to the primed panelfor a dry film build of from 1.0 to 1.2 mils and flashed for 5 minutesat 140 degrees F. Clearcoat compositions VA, VB, VC, VD, VE, and VF werethen spray applied to the flashed basecoated panels in a dry film buildwedge of from 0.1 to 2.0 mils. The applied clearcoat compositions werethen flashed for 20 minutes at room temperature. The panels were thencured for 90 minutes at 300 degrees F. to simulate an overbakecondition. A repair condition was simulated by the application of thepreviously applied black waterborne basecoat to the overbakedclearcoated panels. No scuffy or abrasion was provided to the overbakedclearcoated panels. The ‘repair’ basecoat was applied as indicated abovefollowed by application of the same corresponding clearcoat to theflashed but uncured basecoat. The clearcoat was applied to a dry filmbuild of 2.0 mils. The clearcoat was the flashed for 20 minutes at roomtemperature and baked for 15 minutes at 260 degrees F.

Adhesion was evaluated per GM9071P, hereby incorporated by reference.The results are set forth in Table 2.

TABLE 2 % Nonfunctional % Repair Adhesion Coating Composition MonomerRemaining VA  8.4% 70% VB  8.1% 65% VC  8.2% 50% VD 18.2% 30% VE 28.2%5% VF (Comparative) 55%  0%

It should be noted that “% repair adhesion remaining” identifies theamount of the second or repair basecoat/clearcoat composite compositionwhich remains after the tape pull. The above results primarilyillustrate the effect of % nonfunctional monomer upon repair adhesion.However, the loss of adhesion measured above for coating compositionsVA, VB, VC, VD, and VE is always initiated at the nonexisitent portionof the underlying first clearcoat film build wedge, i.e., where thefirst applied clearcoat has a film build of approximately 0.0 mils.Thus, in these instances, the loss of adhesion is actually reflective ofthe degree of adhesion between the first applied basecoat and the secondapplied basecoat. In fact, coating compositions VA, VB, VC, and VD allshowed 100% adhesion remaining at the recommended film build for thefirst underlying clearcoat composition. In contrast, comparative coatingcomposition VF fails at all film builds of the first underlyingclearcoat film build wedge. That is, none of the subsequently appliedrepair basecoat/clearcoat composite coating adhered to the firstbasecoat/clearcoat composite, regardless of the film build of the firstclearcoat.

EXAMPLE VII Evaluation of Clearcoat Adhesion to Primerless UrethaneWindowshield Adhesive Caulking

Clearcoat compositions VA and VF were evaluated for adhesion to twopolyurethane adhesive calking compounds illustrative of those used bythe automotive industry to adhere windowshield components to a paintedcar frame. The two compounds were Betaseal™ 15618 and Betaseal™ 15706,commercially available from Essex Corporation. Adhesion was evaluatedper the test parameters of GM9522P, hereby incorporated by reference.

Betaseal 15618 Betaseal 15706 Clearcoat Clearcoat Clearcoat ClearcoatClearcoat Bake Bake Bake Bake composition 15′ @ 265 F. 90′ @ 300 F. 15′@ 265 F. 90′@ 300 F. VA F, F Fa, F F, F F, F VF Fa, Fa Fa, Fa Fa, Fa Fa,Fa (Comparative) F = clearcoat to caulk adhesive failure; Fa clearcoatto basecoat adhesive failure

The results showed that in all instances where the control sample VFfailed to adhere to the primerless polyurethane adhesive caulking, theclearcoat composition of the invention adhered to the caulking but onlyfailed with respect to clearcoat/basecoat adhesion. Accordingly, theclearcoat compositions of the invention provide greatly improvedadhesion to primer polyurethane adhesive caulking relative to thatprovided by carbamate clearcoats of the prior art.

EXAMPLE VIII

Another clearcoat composition was prepared using the carbamatefunctional resin of the invention of Example IVA. Clearcoat compositionVIII was identical to that of the clearcoat composition of Example VIAexcept that no Disparlon™ 955 was used. This clearcoat composition wasevaluated for scratch and mar against a control prior art clearcoatcomposition corresponding to clearcoat composition IIA.

Test panels were prepared as indicated in Examples III and VI exceptthat no repair adhesion preparation was done. Two different basecoatswere tested, a waterborne black basecoat commercially available fromBASF Corporation as E202KW706, and medium solids solventborne blackbasecoat commercially available from BASF Coatings AG as VWL041FD80-9103-0101 .

Scratch and mar was evaluated per FLTM BI 161-01, hereby incorporated byreference, using a CM-5 Crockmeter available from Atlas Electric DevicesCo, Chicago Ill. The results are set forth below in Table 3.

TABLE 3 Clearcoat composition Basecoat Control Clearcoat VIII WaterborneBlack BC 52.65 82.8 Solventborne Black BC 43.18 68.1

It can be seen that the clearcoat of the invention provides superiorscratch and mar resistance as compared to the prior art carbamateclearcoat.

We claim:
 1. A carbamate-functional polymer having a backbone made byaddition polymerization, the polymer comprising from at least 66 to 100%by weight, based on the total weight of the carbamate-functionalpolymer, of one or more repeat units A selected from the groupconsisting of

 and mixtures thereof, and from 0 to less than 35% by weight, based onthe total weight of the carbamate-functional polymer, of one or morerepeat units A′ having the structure

the carbamate-functional polymer having an equivalent weight of at least250 grams of polymer per carbamate group, wherein R is an at leastdivalent nonfunctional linking group having from 1 to 60 carbons atomsand from 0 to 20 heteroatoms selected from the group consisting ofoxygen, nitrogen, sulfur, phosphorus, and silane, and mixtures thereof,R′ is an at least monovalent nonfunctional linking group having from 1to 60 carbons atoms and from 0 to 20 heteroatoms selected from the groupconsisting of oxygen, nitrogen, sulfur, phosphorus, and silane, andmixtures thereof, R″ is H or a monovalent nonfunctional linking grouphaving from 1 to 60 carbons atoms and from 0 to 20 heteroatoms selectedfrom the group consisting of oxygen, nitrogen, sulfur, phosphorus, andsilane, and mixtures thereof, L is a divalent nonfunctional linkinggroup having from 1 to 60 carbons atoms and from 0 to 20 heteroatomsselected from the group consisting of oxygen, nitrogen, sulfur,phosphorus, and silane, and mixtures thereof, F, F¹ and F² arefunctional groups selected from the group consisting of primarycarbamate groups, beta-hydroxy primary carbamate groups, hydroxylgroups, and mixtures thereof, with the proviso that at least one of F¹and F² are a primary carbamate group or a beta-hydroxy primary carbamategroup, and n is an integer from 0 to
 3. 2. The polymer of claim 1wherein the at least monovalent nonfunctional linking group R′ comprisesat least one branched alkyl group of a least 5 carbons.
 3. The polymerof claim 2 wherein the at least one branched alkyl group has 10 carbons.4. The polymer of claim 1 wherein R, R′ or R″ comprise one or moregroups selected from the group consisting of esters, amides, secondarycarbamates, ethers, secondary ureas, ketones, aliphatic groups,cycloaliphatic groups, aromatic groups, and mixtures thereof.
 5. Thepolymer of claim 1 wherein R″ is H.
 6. The polymer of claim 1 comprisingless than 20 percent by weight of repeat units A′, based on the totalweight of the carbamate-functional polymer.
 7. The polymer of claim 1comprising less than 10 percent by weight of one or more repeat unitsA′, based on the total weight of the carbamate-functional polymer. 8.The polymer of claim 1 comprising from 1.0 to 9.0 percent by weight ofone or more repeat units A′, based on the total weight of thecarbamate-functional polymer.
 9. The polymer of claim 1 comprising lessthan 1 percent by weight of one or more repeat units A′, based on thetotal weight of the carbamate-functional polymer.
 10. The polymer ofclaim 1 wherein the equivalent weight is from 300 to 550 grams ofpolymer per primary carbamate group.
 11. The polymer of claim 10 havingan equivalent weight of from 350 to 450 grams of polymer per primarycarbamate group.
 12. The polymer of claim 1 wherein one or more of R,R′, or R″ are the reaction product of a functional group of a monomer Aand a compound B having at least one functional group (b1) reactive withthe functional group of monomer A.
 13. The polymer of claim 12 whereincompound B further comprises an additional functional group selectedfrom the group consisting of hydroxy groups, carbamate groups, groupsconvertible to hydroxy groups, and groups convertible to carbamategroups.
 14. The polymer of claim 12 wherein one or more of R, R′, or R″are the reaction product of an acrylic acid group and a glycidyl groupcontaining monomer.
 15. The polymer of claim 1 wherein R is an alkylester group, R′ is a branched alkyl ester group of from 1 to 15 carbons,R″ is selected from the group consisting of hydrogen, aromatic groups,alkyl groups of from 1 to 10 carbons, and mixtures thereof, L isselected from the group consisting of

 and isomers thereof, F, F¹ and F² are selected from the groupconsisting of hydroxyl and primary carbamate, and n is
 0. 16. Thepolymer of claim 15 wherein R is

R′ is

wherein R₁, R₂, and R₃ are alkyl groups of from 1 to 10 carbons.
 17. Thepolymer of claim 15 wherein more than 50% of F¹ are primary carbamategroups and more than 50% of F² are hydroxyl groups.